Caged small animals such as hamsters, gerbils, mice, rats, chipmunks are normally fed dry solid food such as seeds, bone meals, soy four, rice brans, etc., in open dish containers. The food is usually a loose mixture purchased in bulk at pet stores and only a single serving of food is placed in the open dish since small animals tend to play with their food, spilling and kicking it out of the dish and into their cage. Much food is wasted from littering and animal contamination.
Open dishes take up valuable space in small cages and the animals walk or sleep in their food dishes causing food spoilage due to the poor sanitation and molding of the food.
Small animals have very sharp teeth and in fact they must gnaw on objects to prevent their teeth from becoming too large. Rats which do not have objects to chew on can actually develop fangs which interfere with the animal's ability to properly chew their food. Plastic or other soft dishes cannot be used since the animals chew on them until they are unusable.